This invention relates generally to systems for controlling the operation of disk drive units in a computer environment or the like. More particularly, this invention relates to an improved, relatively simple, and relatively economical control system and method for concurrently operating multiple disk drive units in a manner providing a significantly expanded data storage capability.
In recent years, microcomputer equipment particularly such as so-called personal and desk top computers have become extremely popular for a wide variety of business and educational and other uses. Such computers commonly include a main central processor unit having one or more memory storage disks for storage of data. In many modern computers, the storage disk or disks are often provided in the form of "hard" disks as part of a Winchester-type disk drive unit having the storage disks supported in a stack on a common rotary spindle within a substantially sealed disk drive housing. The disks are rotatably driven in unison by a small spindle motor within the disk drive housing, and one or more electromagnetic heads are displaced by a head positioner assembly to traverse surfaces of the rotating disks for purposes of reading and writing data. Such Winchester-type disk drive units have been produced relatively economically for general purposes microcomputer applications. When the disk drive unit is equipped with multiple memory storage disks, the total disk surface area is increased to result in an increased data storage capacity. For example, Winchester-type disk drive units for personal computer applications are currently available with from one to four disks providing data storage capacities in the range of about 5-40 megabytes.
In some specialized applications of personal computers and the like, there is a demand for a significantly expanded data storage capacity. However, practical cost and standardized size constraints have generally prohibited provision of significantly expanded memory capacities, for example, in the range of 75-80 megabytes and higher, in the personal computer environment. By contrast, such memory capacities are available in larger, so-called main frame computers either by the use of significantly larger Winchester disk drive units having a substantially increased number of data storage disks, or by the use of costly digital electronic control arrangements for linking multiple disk drive units in frequency and phase locked relation to permit function as a common memory bank. These approaches to expanded data capacity, however, are generally recognized as impractical in a personal or desk top computer environment as a result of cost and/or size restrictions.
There exists, therefore, a significant need for a system and method for achieving substantial increases in data storage capacity in personal type computer equipment, in a cost- and space-efficient manner. The present invention fulfills these needs and provides further related advantages.